x Abu Dhabi, UAESaturday 22 July 2017

Abu Dhabi's 500 million gallon-a-day question: where is the water going?

Of 650 million gallons of potable water produced every day in Abu Dhabi only 150 million is reclaimed, leading to mystery of where 18.25 billion gallons a year go? Officials now hope to solve the riddle.

ABU DHABI // It’s the 500 million gallon question – where does Abu Dhabi’s potable water go?

A trial expected to start this year could shed more light on why, of all the potable water produced daily in the emirate, less than a quarter returns to the sewage-treatment system.

Investigators plan to track the water use of 200 villas over a period of months in an experiment that could help to redefine what constitutes “essential water use” in an arid region.

Desalination plants process sea water to produce the emirate’s potable supplies, with the brunt of the cost covered by the Government. The procedure has a significant impact on the environment.

In 2011, Abu Dhabi produced 650 million gallons of water a day, according to Nick Carter, director general of the Regulation and Supervision Bureau (RSB).

But only about 150 million gallons a day entered the sewage- treatment system. “The rest is unaccounted for,” he said.

Mr Carter and his colleagues have some answers as to where the 500 million gallons go – into gardens, parks, swimming pools and washing residents’ cars and driveways.

The trial, which will see meters and data loggers installed in volunteers’ homes, aims to put numbers to these uses.
A trial study of five homes last year provided some answers, said Khadija bin Braik, manager of Waterwise, an RSB programme to study habits and promote sustainable water use among residents.

Ms bin Braik said that while the sample was too small for any of the figures to have statistical significance, the trial did show that targeting villa residents was essential to any scheme aiming to reduce water use.

“People residing in villas consume 50 per cent of their water outdoors,” Ms bin Braik said.

According to Mr Carter, reducing non-essential water use could also open the door to more wide-scale water recycling, which would give the emirate larger volumes of treated sewage effluent that could be used for applications not requiring high-quality potable water,   such as irrigating parks.

“There is a huge gap between what is supplied to customers and what returns to the sewer,” he said. “If we can change that gap so that less water is put on the ground ... we can return more water to sewers as a percentage. That water can be reused.

“We can get a double use of water – one in a safe environment in a home or business, and another one where you want to use the water to a less high standard.”

The study is one of a number of steps taken by RSB to address the fast-rising demand for water and electricity in Abu Dhabi.

If the current trajectory were to continue, by 2020 the emirate’s demand for water would be almost double its demand in 2011.

A similar thing is happening in terms of electricity. Last year, peak demand reached 10 gigawatts (GW), but it will reach “at least 20 gigawatts” by 2020, according to Mr Carter.

RSB estimates that 33 per cent of overall energy demand comes from households. In June, it started work on a trial to assess whether pricing energy differently would affect people’s use.

At the end of last year, it installed 400 smart meters in the homes of volunteers whose energy consumption will be monitored.

The experiment is centred around a concept known to experts as peak demand. In Abu Dhabi, for example, because of cooling needs, peak electricity demand during summer is significantly higher than at other times of the year.

There are also daily peaks in energy use. Although such peaks last only a limited amount of time, they must still be accommodated, and this can only be done by the emirate investing in expensive infrastructure.

The trial aims to find out whether people change how they use electricity if it is priced differently at different times of the day.

vtodorova@thenational.ae